There is known to be an electrical junction box in which a double layered circuit board is stored in a case, and the circuit board specifically has a structure in which a sub substrate is arranged on the lower surface side of a main substrate that is provided with terminal fittings and electronic components, and the main substrate and the sub substrate are connected by relay terminals (see cited Patent Document 1 below).
As an example of a manufacturing method of this type of circuit board, first, the terminal fittings used for a connector are provided upright by soldering them to the upper surface of the main substrate, and electronic components are likewise mounted to the upper surface by soldering. Next, the relay terminals are provided upright on the upper surface of the sub substrate by soldering. Then, the sub substrate, on which the relay terminals stand, is arranged on the lower surface side of the main substrate, and the leading ends of the relay terminals are connected to the lower surface of the main substrate by soldering.